The Self-location Technology Research For Wireless Sensor Network

With the development of sensor techniques, low-power electronic and radio techniques, low-power and inexpensive wireless sensors have been put into application, then the wireless sensor networks have appeared. Wireless sensor networks can be applied to many areas, such as military affairs, commerce, medical care, environmental monitoring, and have become a new research focus in computer and communication fields. Many applications of wireless sensor networks are based on sensor self-positioning, such as battlefield surveillance, environment monitoring, indoor user tracking and others, which depend on knowing the location of sensor nodes. Because of the constraint in size, power, and cost of sensor nodes, the investigation of efficient location algorithms which satisfy the basic accuracy requirement for WSN meet new challenges.The location techniqes for WSN can be divided into two categories: Range-based approaches and Range-free approaches. Range-based methods have better accuracy, but require additional hardware at the sensor nodes, which are not available on regular application fort sensor networks. Acknowledging the requirement of hardware cost, the range-based solutions may be inappropriate in relation to the required location precision. Researchers have sought alternate range-free solutions to the localization problem in sensor networks. Because of the hardware limitations of WSN devices, solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches. The range-free algorithms make no assumption about the availability or validity of range information. Because of the advantages on power and cost on sensor node, this thesis focuses the investigation on the range-free algorithms for WSN.First of all, the research status of wireless location techniques and positioning systems for WSN are summarized based on the study of a lot of related literatures. In this thesis, the principles and characteristics of related approaches on WSN are discussed and presented. Second, the criterion of performance evaluation and algorithms, the taxonomy for wireless sensor networks localization systems are described in the thesis, the principles and characteristics of recent representative localization approaches are also discussed and presented. Then, the thesis focuses on the investigation of DV-Hop location algorithm, an improved node positioningalgorithm is proposed, together with the discussion of algorithm principle and realization issues. The proposed method can improve location accuracy and coverage without increasing hardware cost of sensor node. The simulation results show that the performance of this algorithm is significantly improved compared with the DV-Hop algorithm. In the end, it is the conclusion of the thesis and the prospect for the future research work.